A photoresist resin used in a process for producing a semiconductor is in need of a part exhibiting adhesion to substrate such as silicon wafers and a part becoming soluble in an alkali-developer by being eliminated by action of an acid generated from a photosensitive acid generator with exposure. Further, a photoresist resin is in need of having resistance to dry etching.
In Japanese Unexamined Patent Application Publications No. 2000-026446, an alicyclic hydrocarbon skeleton having a lactone skeleton is described as a structure which gives adhesion to a substrate and has resistance to dry-etching. Further, in Japanese Unexamined Patent Application Publications No. 1997-073137, an alicyclic hydrocarbon skeleton having a tertiary carbon atom is proposed as a structure which gives acid-eliminating property and has resistance to dry-etching. Therefore, co-polymerizing monomers having such two skeletons can provide a polymer integrating functions needed for a photoresist resin. The co-polymer has adhesion to substrate, acid-eliminating property and resistance to dry-etching, but its polarity is so low because of having an alicyclic hydrocarbon skeleton that the co-polymer is hard to dissolve in a photoresist solvent and in an alkali-developer after exposure, and other problems can be occurred. Such properties of co-polymer are out of balance as a photoresist resin.